Outside of the rare socket 2011 i7's (the only real i7 IMHO) you get more PCIe lanes and significantly more memory bandwidth with xeons too. The extra PCIe lanes can matter for SLI setups..
But this is where Intel irritates me. I want a socket 2011 CPU with both an unlocked (or low core high clock rate) multiplier as well as ECC RAM. For some reason, intel refuses to make such a product.
I was looking for something similar and indeed there isn't much choice in that department. I eventually switched to the high-core lots-of-performance/per-buck E5-2670 especially considering its low price. But if you want high single thread performance, take a look at E5-1650 or, if you have unlimited budget, E5-1680 v2 (12% faster).
The latest v4 parts have turbo frequencies again peaking at 4ghz. Which when compared with the i7-7700, that is a 12% frequency deficit. If you count in a couple percent between haswell & kaby lake, its probably at least a 15% single thread advantage to the part that costs far less.
Hence the unlocked 2011 parts which people routinely run up in the ~4.5Ghz range (myself included) with little issues. The only point of instability seems to be the larger cache, which can have its multiplier independently limited, at which point the stock voltages suffice for a significant clock rate increases. Why intel couldn't bin and sell a 4.2Ghz 2011 part like devils canyon is a mystery.
But this is where Intel irritates me. I want a socket 2011 CPU with both an unlocked (or low core high clock rate) multiplier as well as ECC RAM. For some reason, intel refuses to make such a product.